A conventional driving mechanism for surgical manipulator is disclosed in, for example, Published Unexamined Patent Application in Japan No. 2007-292 276, which is energized with an input of rotation to make a bending and/or curvature movement on connecting members. With the driving mechanism as cited earlier, the manipulator has a bending link to join adjacent connecting members each other and grasping links. The grasping links are connected to the connecting members against axial direction. The grasping links each have a first shaft and a second shaft, the first shaft having second male threads mating with a second plate of the connecting member and the second shaft having first male threads mating with a first plate of the connecting member. The first and second male threads are made inversely each other with the same pitch. With the relation of the male threads around the shafts, the connecting members moves to approach each other when the bending link is rotated in any one direction, whereas the connecting members moves away from each other when the bending link is rotated in opposite direction.
Moreover, a multi-freedom manipulator is disclosed in, for example, Published Unexamined Patent Application in Japan No. 2005-169 011, which is superior durability and accuracy in control, and further easier in attaching and/or detachability to the sterilizers, washers and driving means. The multi-freedom manipulator has at least three freedom of relative opening/closing movement of a pair of grasping members, rotation of grasping members around a first axis, and rotation of the grasping members around a second axis lying on an imaginary plane perpendicular to the first axis. With the multi-freedom manipulator constructed as stated earlier, the power applied from the actuator is converted through first ˜three link mechanisms into relative opening/closing movement of the grasping members, rotating movement around a first axis and rotating movement around a second axis.
With the prior wire-operated medical manipulator, moreover, the working parts on the foremost ends of the medical forceps are mainly actuated with a wire for power transmission. Because of this, any lag may occur in tensile variation of expansion and/or contraction of the wire. There causes a problem of worse response or follow-up property which would interfere any minute movement. With the prior wire-operated medical manipulator, moreover, there occur any obstacles or troubles of wire-breakage, elongation and so on which would obstacle accurate operation and/or certain power-transmission. With the patent literature recited earlier, the driving mechanism is disclosed in which rotation of the connecting parts is input to actuate the forceps to bend or curve the connecting parts. The limiting universal joints and the driving universal joints are combined to be actuated to get the whole driving part bending. Thus, when the driving mechanism constructed as stated is made small in construction, the housing therefor has to be constituted with three universal joints, with the problems of becoming large in warp and less in rigidity. As a result, the joints can't be bent independently from each other and, therefore, are difficult to make fine movements. The multi-freedom manipulator, because constructed in such that the linkage is driven by fore-and-aft movement transmitted from the actuator and joints are constituted to make bi-axial movement of vertical and sidewise directions, has problems that it is unfit to make fine movement at every joint and the linkage is slender and so long as to lessen in rigidity.
In co-pending Patent Application in Japan No. 2015-34 905, there is disclosed a multi-freedom manipulator which is rich in reliability and follow-up property and operable with high accuracy when used in medical instruments. The multi-freedom manipulator is composed of more than one hollow outer shell, a joint to connect the adjacent outer shells each other in a rocking manner, grasping members mounted to the foremost outer shell to be actuated to hold any object between them, a claw power-transmitting shaft to actuate claws of the grasping members in a rocking manner, and an outer shell power-transmitting shaft to actuate the outer shell in a bending manner. The claw power-transmitting shaft and the outer shell power-transmitting shaft are each composed of a foldable universal joint to transmit a torque, and an expandable power-transmitting shaft to transmit a torque. The power-transmitting shaft has male threads mated with a nut made in a boss portion inside the outer shell.